Mounted in the middle of Charlie Kimball's steering wheel is the most important gauge in his race car. It has nothing to do with telling him how fast he's going or how much fuel he has left. In fact, it has nothing to do with his race car at all.

This gauge tells him what his blood sugar levels are. Without it, he couldn't race, and certainly wouldn't have been the first Type-1 diabetic ever to compete in the Indianapolis 500.

Professional athletes with diabetes are certainly rare, but not unheard of. Chicago Bears quarterback Jay Cutler is diabetic. So is Olympic swimmer Gary Hall Jr. There's even a diabetic in the NASCAR Camping World Truck Series -- Miguel Paludo. They all face the daily challenge of managing a disease that's a perpetually moving target.

But it's one thing to do this with the benefit of intermissions or 60-second shifts; quite another when you're sitting in a race car and expected to manage your health at 200 mph without the promise of a single timeout for several hours.

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So while everyone else on the track is going through the motions of checking their fuel gauge and monitoring their engine temperature, Kimball has the added responsibility of keeping an eye on his blood sugar level, because the potential ramifications are serious -- and not just for him.

If his blood sugars stray high, his reaction time could be slowed. If they drop, he could become lightheaded, lose focus and, in the worst-case scenario, pass out.

"That's something that is totally unacceptable," Kimball says. "There are 32 other drivers on the track and I'm not willing to ask them to take that risk. I understand that I have to be extremely responsible about this, because it's not just my safety on the line; it's other drivers' as well."

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An estimated 25.8 million Americans (7 million of which are undiagnosed) have diabetes. Of these, about 1.5 to 2 million are considered Type-1, meaning their pancreas does not produce insulin to normalize their blood sugar count.

Most Type-1 diabetics are diagnosed as children -- hence the term Juvenile Diabetes. Some, like Kimball, are diagnosed later in life.

He was 22, seemingly in good health, until one day he went to a doctor over a concern about a rash, stepped on a scale and realized he'd lost 25 pounds in one week.

"[The doctor] drew some blood, did some tests and told me I had diabetes," Kimball explains. "I was like, 'What's that?' "

Initially, Kimball thought it was a good thing. He'd finally gotten an answer to why he was feeling lethargic, why he was drinking six to 10 bottles of water before going to bed every night. "I didn't realize it was something more than just taking a pill to get better," he says. "Then he told me it's manageable, not curable."

Kimball quickly learned what that meant: counting the carbohydrates in everything he eats, calculating how much insulin he needed to account for those carbs, then administering what is hopefully the right dosage of insulin.

He also began the six-to-eight-time-a-day ritual of the diabetic: Prick a finger with a needle, squeeze blood out of the hole, press the finger against a test strip attached to a monitor and hope for good news.

If the monitor spits out a level of 110, good. 250, not so good. 50. Well, if your blood sugar level is at 50, you already knew the news wasn't going to be good. The sweat on the back of your neck told you so; so did the lightheadedness.

Technology has helped. Insulin pumps can serve as a sort of back-up pancreas, feeding the body insulin through a tube when need be. Continuous glucose monitors measure one's blood sugars every few minutes. If the blood sugars go high or low, the CGM sends a warning that you need insulin (when high) or sugar (when low).

But even with technology, managing diabetes is anything but exact.

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A day or two before every race, Kimball, 26, puts on a CGM. It's a half-dollar-sized device that's taped somewhere on the body, usually around the stomach. It contains a sensor that is inserted into the body using a needle.

Once calibrated, the CGM sends frequent blood sugar measurements to another device. For some, it's the insulin pump. For others, it's a separate device, about the size of a cell phone.

Kimball doesn't use a pump. For him, it's not feasible. The heat inside the cockpit of his race car would spoil the insulin, rendering it useless. His main line of defense against fluctuating blood sugars is pre-race management and in-car fluids.

Working with Dr. Anne Peters, a diabetes specialist at the University of Southern California, Kimball has developed a dietary and pre-race preparation plan aimed at stabilizing his blood sugar levels.

His cars are equipped with two bottles of fluids -- one containing water, the other a high-carb drink. As long as his blood sugar levels are within a normal range, he sticks with water. If they go low, he switches to the high-carb drink. If they go high, he'll head to pit road where a crew member would stab him with an insulin shot.

Since being diagnosed in 2007, Kimball has never had an incident during a race in which he needed a shot or even the high-carb fluid.

"Having lived with it for 3 ½ years, managing it is almost second nature," he says. "When I'm in the car, especially early in a race, I check the sensor every few laps. If things are going to plan, I check less and less often. Just like checking the telemetry or the fuel mileage, blood sugar is just another sensor to think about. If it's OK, I file that away. It doesn't effect what I'm doing in the cockpit."

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Kimball had to be licensed by IndyCar before he was allowed to compete as a rookie this season. When he showed up to Indianapolis in May, it meant becoming the first Type-1 diabetic to ever seek entry into the Indianapolis 500, which was a big deal on multiple fronts.

From a strictly racing perspective, it meant competing in one of the world's greatest sporting events. From a health perspective, it presented the challenge of managing his diabetes for a three-plus hour event -- or an hour longer than any other race on the IndyCar schedule.

"It was uncharted territory," says Kimball.

With his two teams backing him -- his race team and his diabetes team -- Kimball started 28th. The worry going in was the stress of the race would increase his blood sugars. With Peters on site to monitor his condition, his crew was prepared to administer an insulin shot if need be. That situation never materialized.

Kimball's target blood sugar level was 200. When he climbed out of the cockpit, having finished 13th -- the second-highest finishing rookie -- his blood sugar level was 199.

"It took a ton of work to get Charlie where he is right now," Peters says. "It's such a serious proposition."

But, she notes, "Charlie has it down."

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